Brake mechanism



Dec 31 BRAKE MECHANISM Filed Aug. 5I 1939 QN n@ Q AN @N Q NN glu/vanto@ Hommel-D.. lluhljO/mylv Patented Dec. 3l, 1940 Bendix-Westinghouse Automotive Air' Brake Company, Pittsburgh, Pa., a. corporation of Dela- Ware Application August 5, 1939, serial No. 288,659

4 Claims.

invention relates to brake operating mechanism for vehicles, and more particularly to a slack adjusting device of the worm gear type.

One of the objects of the invention is to provide 5 a slack adjusting device of.simple and inexpensive construction which may be readily incorporated in the linkage of a. vehicle brake system to take up the slack therein caused by brake wear. Another object is toprovide, ina device of the l above type, a novel and eiilcient structure serving to locate and maintain the worm gears in proper meshing'relationship at all times.

A further object is to provide, in a slack adjuster of the above character, a novel body or casing l member for supporting the worm gears` These and other objects and novel features of the invention will appear more fully hereinafter from the following detailed description when taken in connection with the accompanying drawing. 20 It is to be expressly understood, however, that the drawing is'employed for purposes of illustration only and is not designed as a definition of thelimits of the invention, reference being had for this purpose to the appended claims.

In the drawing, wherein similar reference characiers refer to similar parts in the different viewsz.

operating lever 1 which may be formed integrally therewith, one portion ofthe member-having a relatively large bore 8 therethrough together with a channel 9 formed `in the wall of thebore coextensive axially therewith and having parallel walls Ill intersecting the wall ofA the bore. A relatively large worm gear or wheel I I is positioned in the bore 8 for rotation therein and is adapted to engage a relatively small worm I2 positioned in channel 9 with its axis at right ang'lesto and l spacedAirom the axis-of worm wheel il land held against axial movement by virtue of its location between theparallel walls I0 o f channel 9i- In order that the worm I2 may be held against radial movement and maintained in-proper meshing engagement with. the worm wheel II at all' times, a second bore I3 positioned at right angles to the bore 8 is formed in the body so'as to intersect sidewalls I0 of channel s and provide bearings for a rotating worm shaft I4 mounted therein and having a portion in engagement with abore I formed in the worm I2. Although driving engagement between the worm I2 and shaft Il may (Cl. 'I4-522) be effected in a number of ways. this is accomplished in the illustrated embodiment of the invention by so dimensioning the diameters of the shaft I4 and the bore I5 of the worm that, on insertion of the shaft Il in bore I3, the shaft must be forced through the bore of the worm, thus providing not. only a so-called press iit between the parts and establishing a substantially positive driving connection therebetween, but at the same time rendering the worm eifective for maintaining the shaft lI4 longitudinally in the position shown, by virtue of the frictional connection between the partsl and the abutment of worm l2 with channel walls I0, and without the need for additional and relatively expensive worm shaft retaining parts such as have been necessary in connection with slack adjusting devices previously proposed.

For convenience in assembling the above described parts, the bore I3 as shown is formed with a portion I6 of slightly reduced diameter, and a portion I'I of shaft I4 has a correspondingly reduced diameter, making it-unnecessary to prs this portion through the worm when the parts are being assembled. The worm shaft is provided at its lower end with flat portions IB for receiving a wrench for adjusting the position of the shaft and worm, and is normally held against rotation by means of a spring pressed detent comprising a ball I9 carried in a bore 20 in the body and pressed into one of the depressions 2I in shaft I4 by a spring 22 interposed between the ball and an abutment member 23 adapted to be threadedly received by the bore. The entrance of dirt and water into the upper end of bore i3 may be readily prevented' as by means of a plug 24 of the so-called Welsh type inserted in a counterbore 25 formed in the body.

With the slack adjuster parts assembled as heretofore described, the assembly iscompleted by the addition of plates 26 which may be attached to body 6 as by means of rivets A2i inserted through holes 29 in the body, these plates serving to close the ends of bore 8 and channel 9 as well ai toprevent axial movement of the. worm wheel permit driving engagement of a brake operating shaft, not shown, with asuitablesplined bore 30 providedinworm wheel I I, and lever arm 'I is provided with clevis pin holes 3| in order to provide means for connecting the brake operating mechanism. not shown, to the lever.

It will be readily apparent from the foregoing description that there has. been provided by the present invention an eicient slack adjusting de- Apertures 29 are provided in plates 26 to vice whereby the slack due to braise wear may be compensated for by rotating the worm I2 by means of ,worm shaft M for imparting corresponding rotation to worm wheel Il and varying the angular relation between lever arm, 1 and the worm wheel. This desirable end has been accomplished with avminimum number .ofl parts, by providing a body member formed to limit -radial and axial movement of the worm wheel and worm respectively, the addition of a worm shaft in frictional engagement with the bore ofthe worm and a pair of cover plates carried by the housing serving, in cooperation with the novel body structure, to maintain the worm gears and worm shaft in their normal operating relationship and to protect the bears from the harmful action of dirt and other foreign substances.'

While an embodiment of the invention has been illustrated and described with considerable particularity, it is to be understood that the invention is not restricted thereto but is capable of receiving a variety of expressions, some of which will now readily suggest themselvesto those skilled in the art, while changes may be made in the details of construction and arrangement of parts, and certain' features used without other features, without departing from thespirit of the invention. Reference is, therefore, to be had to the claims hereto appended for a denition of the limits of the invention.

What is claimed is:

1. A slack adjuster for'brakes comprising a body having a brake lever; a worm wheel and worm, a bore extending through saldbody for rotatably supporting said worm wheel, a channel formed in thewall of said bore and coextensive therewith vfor receiving theworm and preventing axial movement thereof, a pair oi, cover plates carried by the body for closing the ends of the channel and preventing axial movement of said worm wheel in said bore, and meansfor positioningl and operating said worm in driving engagementwith said worm wheel including a second bore in said body and a shaft rotatably mounted therein having a portion in frictional engagement with said worm.

2. A slack adjuster for brakes comprising a body having a brake lever, a bore extending through said body and a worm wheel rotatably mounted therein, a second bore in said body at right angles to said first named bore and axially therefrom, a channel formed in the wall of said first named bore coextensive therewith and having parallel side walls\i ntersecting the wall of said -second named bore in planes perpendicular thereto, aworm having abore there'-' through mounted inl said. channel and having parallelend faces in abutting relationship with said side walls-...closure members can'ied by the body for closing .the ends of said channel and preventingy axial movement of-saidl'worm'wheel, and a shaft rotatably mounted in said second named bore and extending through the bore of said worm for positioning and maintaining said worm in meshing relationship with said worm wheel and having 'a' portionin frictional engagement with the bore of said worm for preventing relative axial movements of said worm and shaft.

3. A slack adjuster for brakes comprising a nel and maintained in meshing engagement with i the. worm wheel by said shaft, the bore ,of the worm being in frictional engagement with a portion of the shaft for preventing relative rotational and axial movement therebetween. and the ends of the worm abutting the parallel side wall u portions of the channel for preventing axial movement of the worm. j

'4. A slack adjuster for brakes comprising a bodyhaving a brake lever,aworm wheel,aworm,

a bore in said body for rotatably supporting said do' worm wheel, a channel formed inthewall of said bore coextensive therewith andhaving substantially parallel walls for receiving said worm and preventing axial movement thereof, closure means carried by the body for preventing axial movementl of said worm wheel in said bore, a second bore in saidv body, a shaft rotatably mounted in said bore, and means connecting said-shaft and worm for preventing relative rotational and axial movement therebetween. 

